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本篇文章給大家分享的是有關(guān)怎樣實(shí)現(xiàn)kubeproxy源碼分析，小編覺得挺實(shí)用的，因此分享給大家學(xué)習(xí)，希望大家閱讀完這篇文章后可以有所收獲，話不多說，跟著小編一起來看看吧。
kubernetes離線安裝包
ipvs相對(duì)于iptables模式具備較高的性能與穩(wěn)定性, 本文講以此模式的源碼解析為主，如果想去了解iptables模式的原理，可以去參考其實(shí)現(xiàn)，架構(gòu)上無差別。
kube-proxy主要功能是監(jiān)聽service和endpoint的事件，然后下放代理策略到機(jī)器上。 底層調(diào)用docker/libnetwork, 而libnetwork最終調(diào)用了netlink 與netns來實(shí)現(xiàn)ipvs的創(chuàng)建等動(dòng)作
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代碼入口：cmd/kube-proxy/app/server.go Run() 函數(shù)
通過命令行參數(shù)去初始化proxyServer的配置
proxyServer, err := NewProxyServer(o)
type ProxyServer struct {
// k8s client
Client clientset.Interface
EventClient v1core.EventsGetter
// ipvs 相關(guān)接口
IptInterface utiliptables.Interface
IpvsInterface utilipvs.Interface
IpsetInterface utilipset.Interface
// 處理同步時(shí)的處理器
Proxier proxy.ProxyProvider
// 代理模式，ipvs iptables userspace kernelspace(windows)四種
ProxyMode string
// 配置同步周期
ConfigSyncPeriod time.Duration
// service 與 endpoint 事件處理器
ServiceEventHandler config.ServiceHandler
EndpointsEventHandler config.EndpointsHandler
}Proxier是主要入口，抽象了兩個(gè)函數(shù)：
type ProxyProvider interface {
// Sync immediately synchronizes the ProxyProvider's current state to iptables.
Sync()
// 定期執(zhí)行
SyncLoop()
}ipvs 的interface 這個(gè)很重要：
type Interface interface {
// 刪除所有規(guī)則
Flush() error
// 增加一個(gè)virtual server
AddVirtualServer(*VirtualServer) error
UpdateVirtualServer(*VirtualServer) error
DeleteVirtualServer(*VirtualServer) error
GetVirtualServer(*VirtualServer) (*VirtualServer, error)
GetVirtualServers() ([]*VirtualServer, error)
// 給virtual server加個(gè)realserver, 如 VirtualServer就是一個(gè)clusterip realServer就是pod(或者自定義的endpoint)
AddRealServer(*VirtualServer, *RealServer) error
GetRealServers(*VirtualServer) ([]*RealServer, error)
DeleteRealServer(*VirtualServer, *RealServer) error
}我們?cè)谙挛脑僭敿?xì)看ipvs_linux是如何實(shí)現(xiàn)上面接口的
virtual server與realserver, 最重要的是ip:port，然后就是一些代理的模式如sessionAffinity等:
type VirtualServer struct {
Address net.IP
Protocol string
Port uint16
Scheduler string
Flags ServiceFlags
Timeout uint32
}
type RealServer struct {
Address net.IP
Port uint16
Weight int
}創(chuàng)建apiserver client
client, eventClient, err := createClients(config.ClientConnection, master)
創(chuàng)建Proxier 這是僅僅關(guān)注ipvs模式的proxier
else if proxyMode == proxyModeIPVS {
glog.V(0).Info("Using ipvs Proxier.")
proxierIPVS, err := ipvs.NewProxier(
iptInterface,
ipvsInterface,
ipsetInterface,
utilsysctl.New(),
execer,
config.IPVS.SyncPeriod.Duration,
config.IPVS.MinSyncPeriod.Duration,
config.IPTables.MasqueradeAll,
int(*config.IPTables.MasqueradeBit),
config.ClusterCIDR,
hostname,
getNodeIP(client, hostname),
recorder,
healthzServer,
config.IPVS.Scheduler,
)
...
proxier = proxierIPVS
serviceEventHandler = proxierIPVS
endpointsEventHandler = proxierIPVS這個(gè)Proxier具備以下方法：
+OnEndpointsAdd(endpoints *api.Endpoints) +OnEndpointsDelete(endpoints *api.Endpoints) +OnEndpointsSynced() +OnEndpointsUpdate(oldEndpoints, endpoints *api.Endpoints) +OnServiceAdd(service *api.Service) +OnServiceDelete(service *api.Service) +OnServiceSynced() +OnServiceUpdate(oldService, service *api.Service) +Sync() +SyncLoop()
所以ipvs的這個(gè)Proxier實(shí)現(xiàn)了我們需要的絕大部分接口
小結(jié)一下：
+-----------> endpointHandler | +-----------> serviceHandler | ^ | | +-------------> sync 定期同步等 | | | ProxyServer---------> Proxier --------> service 事件回調(diào) | | | +-------------> endpoint事件回調(diào) | | 觸發(fā) +-----> ipvs interface ipvs handler <-----+
檢查是不是帶了clean up參數(shù)，如果帶了那么清除所有規(guī)則退出
OOM adjuster貌似沒實(shí)現(xiàn)，忽略
resouceContainer也沒實(shí)現(xiàn)，忽略
啟動(dòng)metrics服務(wù)器，這個(gè)挺重要，比如我們想監(jiān)控時(shí)可以傳入這個(gè)參數(shù), 包含promethus的 metrics. metrics-bind-address參數(shù)
啟動(dòng)informer, 開始監(jiān)聽事件，分別啟動(dòng)協(xié)程處理。
1 2 3 4我們都不用太關(guān)注，細(xì)看5即可：
informerFactory := informers.NewSharedInformerFactory(s.Client, s.ConfigSyncPeriod) serviceConfig := config.NewServiceConfig(informerFactory.Core().InternalVersion().Services(), s.ConfigSyncPeriod) // 注冊(cè) service handler并啟動(dòng) serviceConfig.RegisterEventHandler(s.ServiceEventHandler) // 這里面僅僅是把ServiceEventHandler賦值給informer回調(diào) go serviceConfig.Run(wait.NeverStop) endpointsConfig := config.NewEndpointsConfig(informerFactory.Core().InternalVersion().Endpoints(), s.ConfigSyncPeriod) // 注冊(cè)endpoint endpointsConfig.RegisterEventHandler(s.EndpointsEventHandler) go endpointsConfig.Run(wait.NeverStop) go informerFactory.Start(wait.NeverStop)
serviceConfig.Run與endpointConfig.Run僅僅是給回調(diào)函數(shù)賦值, 所以注冊(cè)的handler就給了informer, informer監(jiān)聽到事件時(shí)就會(huì)回調(diào)：
for i := range c.eventHandlers {
glog.V(3).Infof("Calling handler.OnServiceSynced()")
c.eventHandlers[i].OnServiceSynced()
}那么問題來了，注冊(cè)進(jìn)去的這個(gè)handler是啥？ 回顧一下上文的
serviceEventHandler = proxierIPVS endpointsEventHandler = proxierIPVS
所以都是這個(gè)proxierIPVS
handler的回調(diào)函數(shù), informer會(huì)回調(diào)這幾個(gè)函數(shù)，所以我們?cè)谧约洪_發(fā)時(shí)實(shí)現(xiàn)這個(gè)interface注冊(cè)進(jìn)去即可：
type ServiceHandler interface {
// OnServiceAdd is called whenever creation of new service object
// is observed.
OnServiceAdd(service *api.Service)
// OnServiceUpdate is called whenever modification of an existing
// service object is observed.
OnServiceUpdate(oldService, service *api.Service)
// OnServiceDelete is called whenever deletion of an existing service
// object is observed.
OnServiceDelete(service *api.Service)
// OnServiceSynced is called once all the initial even handlers were
// called and the state is fully propagated to local cache.
OnServiceSynced()
}go informerFactory.Start(wait.NeverStop)
這里執(zhí)行后，我們創(chuàng)建刪除service endpoint等動(dòng)作都會(huì)被監(jiān)聽到，然后回調(diào),回顧一下上面的圖，最終都是由Proxier去實(shí)現(xiàn)，所以后面我們重點(diǎn)關(guān)注Proxier即可
s.Proxier.SyncLoop()
然后開始SyncLoop,下文開講
我們創(chuàng)建一個(gè)service時(shí)OnServiceAdd方法會(huì)被調(diào)用, 這里記錄一下之前的狀態(tài)與當(dāng)前狀態(tài)兩個(gè)東西，然后發(fā)個(gè)信號(hào)給syncRunner讓它去處理：
func (proxier *Proxier) OnServiceAdd(service *api.Service) {
namespacedName := types.NamespacedName{Namespace: service.Namespace, Name: service.Name}
if proxier.serviceChanges.update(&namespacedName, nil, service) && proxier.isInitialized() {
proxier.syncRunner.Run()
}
}記錄service 信息,可以看到?jīng)]做什么事，就是把service存在map里, 如果沒變直接刪掉map信息不做任何處理：
change, exists := scm.items[*namespacedName]
if !exists {
change = &serviceChange{}
// 老的service信息
change.previous = serviceToServiceMap(previous)
scm.items[*namespacedName] = change
}
// 當(dāng)前監(jiān)聽到的service信息
change.current = serviceToServiceMap(current)
如果一樣，直接刪除
if reflect.DeepEqual(change.previous, change.current) {
delete(scm.items, *namespacedName)
}proxier.syncRunner.Run() 里面就發(fā)送了一個(gè)信號(hào)
select {
case bfr.run <- struct{}{}:
default:
}這里面處理了這個(gè)信號(hào)
s.Proxier.SyncLoop()
func (proxier *Proxier) SyncLoop() {
// Update healthz timestamp at beginning in case Sync() never succeeds.
if proxier.healthzServer != nil {
proxier.healthzServer.UpdateTimestamp()
}
proxier.syncRunner.Loop(wait.NeverStop)
}runner里收到信號(hào)執(zhí)行，沒收到信號(hào)會(huì)定期執(zhí)行：
func (bfr *BoundedFrequencyRunner) Loop(stop <-chan struct{}) {
glog.V(3).Infof("%s Loop running", bfr.name)
bfr.timer.Reset(bfr.maxInterval)
for {
select {
case <-stop:
bfr.stop()
glog.V(3).Infof("%s Loop stopping", bfr.name)
return
case <-bfr.timer.C(): // 定期執(zhí)行
bfr.tryRun()
case <-bfr.run:
bfr.tryRun() // 收到事件信號(hào)執(zhí)行
}
}
}這個(gè)bfr runner里我們最需要主意的是一個(gè)回調(diào)函數(shù)，tryRun里檢查這個(gè)回調(diào)是否滿足被調(diào)度的條件：
type BoundedFrequencyRunner struct {
name string // the name of this instance
minInterval time.Duration // the min time between runs, modulo bursts
maxInterval time.Duration // the max time between runs
run chan struct{} // try an async run
mu sync.Mutex // guards runs of fn and all mutations
fn func() // function to run, 這個(gè)回調(diào)
lastRun time.Time // time of last run
timer timer // timer for deferred runs
limiter rateLimiter // rate limiter for on-demand runs
}
// 傳入的proxier.syncProxyRules這個(gè)函數(shù)
proxier.syncRunner = async.NewBoundedFrequencyRunner("sync-runner", proxier.syncProxyRules, minSyncPeriod, syncPeriod, burstSyncs)這是個(gè)600行左右的搓逼函數(shù)，也是處理主要邏輯的地方。
設(shè)置一些iptables規(guī)則，如mark與comment
確定機(jī)器上有網(wǎng)卡，ipvs需要綁定地址到上面
確定有ipset，ipset是iptables的擴(kuò)展，可以給一批地址設(shè)置iptables規(guī)則 ...(又臭又長，重復(fù)代碼多，看不下去了，細(xì)節(jié)問題自己去看吧)
我們最關(guān)注的，如何去處理VirtualServer的
serv := &utilipvs.VirtualServer{
Address: net.ParseIP(ingress.IP),
Port: uint16(svcInfo.port),
Protocol: string(svcInfo.protocol),
Scheduler: proxier.ipvsScheduler,
}
if err := proxier.syncService(svcNameString, serv, false); err == nil {
if err := proxier.syncEndpoint(svcName, svcInfo.onlyNodeLocalEndpoints, serv); err != nil {
}
}看下實(shí)現(xiàn), 如果沒有就創(chuàng)建，如果已存在就更新, 給網(wǎng)卡綁定service的cluster ip：
func (proxier *Proxier) syncService(svcName string, vs *utilipvs.VirtualServer, bindAddr bool) error {
appliedVirtualServer, _ := proxier.ipvs.GetVirtualServer(vs)
if appliedVirtualServer == nil || !appliedVirtualServer.Equal(vs) {
if appliedVirtualServer == nil {
if err := proxier.ipvs.AddVirtualServer(vs); err != nil {
return err
}
} else {
if err := proxier.ipvs.UpdateVirtualServer(appliedVirtualServer); err != nil {
return err
}
}
}
// bind service address to dummy interface even if service not changed,
// in case that service IP was removed by other processes
if bindAddr {
_, err := proxier.netlinkHandle.EnsureAddressBind(vs.Address.String(), DefaultDummyDevice)
if err != nil {
return err
}
}
return nil
}現(xiàn)在可以去看ipvs的AddVirtualServer的實(shí)現(xiàn)了，主要是利用socket與內(nèi)核進(jìn)程通信做到的。 pkg/util/ipvs/ipvs_linux.go 里 runner結(jié)構(gòu)體實(shí)現(xiàn)了這些方法, 這里用到了 docker/libnetwork/ipvs庫：
// runner implements Interface.
type runner struct {
exec utilexec.Interface
ipvsHandle *ipvs.Handle
}
// New returns a new Interface which will call ipvs APIs.
func New(exec utilexec.Interface) Interface {
ihandle, err := ipvs.New("") // github.com/docker/libnetwork/ipvs
if err != nil {
glog.Errorf("IPVS interface can't be initialized, error: %v", err)
return nil
}
return &runner{
exec: exec,
ipvsHandle: ihandle,
}
}New的時(shí)候創(chuàng)建了一個(gè)特殊的socket, 這里與我們普通的socket編程無差別，關(guān)鍵是syscall.AF_NETLINK這個(gè)參數(shù)，代表與內(nèi)核進(jìn)程通信：
sock, err := nl.GetNetlinkSocketAt(n, netns.None(), syscall.NETLINK_GENERIC)
func getNetlinkSocket(protocol int) (*NetlinkSocket, error) {
fd, err := syscall.Socket(syscall.AF_NETLINK, syscall.SOCK_RAW|syscall.SOCK_CLOEXEC, protocol)
if err != nil {
return nil, err
}
s := &NetlinkSocket{
fd: int32(fd),
}
s.lsa.Family = syscall.AF_NETLINK
if err := syscall.Bind(fd, &s.lsa); err != nil {
syscall.Close(fd)
return nil, err
}
return s, nil
}創(chuàng)建一個(gè)service, 轉(zhuǎn)換成docker service格式，直接調(diào)用:
// AddVirtualServer is part of Interface.
func (runner *runner) AddVirtualServer(vs *VirtualServer) error {
eSvc, err := toBackendService(vs)
if err != nil {
return err
}
return runner.ipvsHandle.NewService(eSvc)
}然后就是把service信息打包，往socket里面寫即可：
func (i *Handle) doCmdwithResponse(s *Service, d *Destination, cmd uint8) ([][]byte, error) {
req := newIPVSRequest(cmd)
req.Seq = atomic.AddUint32(&i.seq, 1)
if s == nil {
req.Flags |= syscall.NLM_F_DUMP //Flag to dump all messages
req.AddData(nl.NewRtAttr(ipvsCmdAttrService, nil)) //Add a dummy attribute
} else {
req.AddData(fillService(s))
} // 把service塞到請(qǐng)求中
if d == nil {
if cmd == ipvsCmdGetDest {
req.Flags |= syscall.NLM_F_DUMP
}
} else {
req.AddData(fillDestinaton(d))
}
// 給內(nèi)核進(jìn)程發(fā)送service信息
res, err := execute(i.sock, req, 0)
if err != nil {
return [][]byte{}, err
}
return res, nil
}構(gòu)造請(qǐng)求
func newIPVSRequest(cmd uint8) *nl.NetlinkRequest {
return newGenlRequest(ipvsFamily, cmd)
}在構(gòu)造請(qǐng)求時(shí)傳入的是ipvs協(xié)議簇
然后構(gòu)造一個(gè)與內(nèi)核通信的消息頭
func NewNetlinkRequest(proto, flags int) *NetlinkRequest {
return &NetlinkRequest{
NlMsghdr: syscall.NlMsghdr{
Len: uint32(syscall.SizeofNlMsghdr),
Type: uint16(proto),
Flags: syscall.NLM_F_REQUEST | uint16(flags),
Seq: atomic.AddUint32(&nextSeqNr, 1),
},
}
}給消息加Data,這個(gè)Data是個(gè)數(shù)組，需要實(shí)現(xiàn)兩個(gè)方法：
type NetlinkRequestData interface {
Len() int // 長度
Serialize() []byte // 序列化, 內(nèi)核通信也需要一定的數(shù)據(jù)格式，service信息也需要實(shí)現(xiàn)
}比如 header是這樣序列化的, 一看愣住了，思考好久才看懂： 拆下看： ([unsafe.Sizeof(hdr)]byte) 一個(gè)[]byte類型，長度就是結(jié)構(gòu)體大小 (unsafe.Pointer(hdr))把結(jié)構(gòu)體轉(zhuǎn)成byte指針類型 加個(gè)取它的值 用[:]轉(zhuǎn)成byte返回
func (hdr *genlMsgHdr) Serialize() []byte {
return (*(*[unsafe.Sizeof(*hdr)]byte)(unsafe.Pointer(hdr)))[:]
}發(fā)送service信息給內(nèi)核
一個(gè)很普通的socket發(fā)送接收數(shù)據(jù)
func execute(s *nl.NetlinkSocket, req *nl.NetlinkRequest, resType uint16) ([][]byte, error) {
var (
err error
)
if err := s.Send(req); err != nil {
return nil, err
}
pid, err := s.GetPid()
if err != nil {
return nil, err
}
var res [][]byte
done:
for {
msgs, err := s.Receive()
if err != nil {
return nil, err
}
for _, m := range msgs {
if m.Header.Seq != req.Seq {
continue
}
if m.Header.Pid != pid {
return nil, fmt.Errorf("Wrong pid %d, expected %d", m.Header.Pid, pid)
}
if m.Header.Type == syscall.NLMSG_DONE {
break done
}
if m.Header.Type == syscall.NLMSG_ERROR {
error := int32(native.Uint32(m.Data[0:4]))
if error == 0 {
break done
}
return nil, syscall.Errno(-error)
}
if resType != 0 && m.Header.Type != resType {
continue
}
res = append(res, m.Data)
if m.Header.Flags&syscall.NLM_F_MULTI == 0 {
break done
}
}
}
return res, nil
}Service 數(shù)據(jù)打包 這里比較細(xì)，核心思想就是內(nèi)核只認(rèn)一定格式的標(biāo)準(zhǔn)數(shù)據(jù)，我們把service信息按其標(biāo)準(zhǔn)打包發(fā)送給內(nèi)核即可。 至于怎么打包的就不詳細(xì)講了。
func fillService(s *Service) nl.NetlinkRequestData {
cmdAttr := nl.NewRtAttr(ipvsCmdAttrService, nil)
nl.NewRtAttrChild(cmdAttr, ipvsSvcAttrAddressFamily, nl.Uint16Attr(s.AddressFamily))
if s.FWMark != 0 {
nl.NewRtAttrChild(cmdAttr, ipvsSvcAttrFWMark, nl.Uint32Attr(s.FWMark))
} else {
nl.NewRtAttrChild(cmdAttr, ipvsSvcAttrProtocol, nl.Uint16Attr(s.Protocol))
nl.NewRtAttrChild(cmdAttr, ipvsSvcAttrAddress, rawIPData(s.Address))
// Port needs to be in network byte order.
portBuf := new(bytes.Buffer)
binary.Write(portBuf, binary.BigEndian, s.Port)
nl.NewRtAttrChild(cmdAttr, ipvsSvcAttrPort, portBuf.Bytes())
}
nl.NewRtAttrChild(cmdAttr, ipvsSvcAttrSchedName, nl.ZeroTerminated(s.SchedName))
if s.PEName != "" {
nl.NewRtAttrChild(cmdAttr, ipvsSvcAttrPEName, nl.ZeroTerminated(s.PEName))
}
f := &ipvsFlags{
flags: s.Flags,
mask: 0xFFFFFFFF,
}
nl.NewRtAttrChild(cmdAttr, ipvsSvcAttrFlags, f.Serialize())
nl.NewRtAttrChild(cmdAttr, ipvsSvcAttrTimeout, nl.Uint32Attr(s.Timeout))
nl.NewRtAttrChild(cmdAttr, ipvsSvcAttrNetmask, nl.Uint32Attr(s.Netmask))
return cmdAttr
}Service總體來講代碼比較簡(jiǎn)單，但是覺得有些地方實(shí)現(xiàn)的有點(diǎn)繞，不夠簡(jiǎn)單直接。 總體來說就是監(jiān)聽apiserver事件，然后比對(duì) 處理，定期也會(huì)去執(zhí)行同步策略。
以上就是怎樣實(shí)現(xiàn)kubeproxy源碼分析，小編相信有部分知識(shí)點(diǎn)可能是我們?nèi)粘９ぷ鲿?huì)見到或用到的。希望你能通過這篇文章學(xué)到更多知識(shí)。更多詳情敬請(qǐng)關(guān)注億速云行業(yè)資訊頻道。
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